Environmental concerns have modified the operating procedure and apparatus necessary for an oil well or a hydrocarbon gas-producing well by limiting the ability of the operator to dump undesirable liquid and solids on the land surface. In well-drilling and hydrocarbon-extracting operations, the materials delivered to the surface usually include liquid hydrocarbon, salt water, hydrocarbon gasses, and solid particles of debris. The usable parts of the flow from the well include the hydrocarbon liquid and the hydrocarbon gas. Gas is separated from the liquid because the gas may be sold without further treatment. The liquid must be stored in a suitable container or containers and removed from the well site for further processing.
Conventional oil well apparatus at a well site includes an oil storage tank, a separator and associated valves and piping. The patent to McNabb, No. 4,597,437, discloses a storage tank, a separator tank and other piping apparatus mounted as a unit on a frame to be transported to the well site.
Flow meters in the form of orifice meters have been around for many years and the patent to Bailey, No. 1,248,057, is illustrative. It shows a duct joined together by a pair of flanges, and between the flanges is clamped a plate having a centrally located orifice. Gas flows through the duct and through the orifice. Two openings are made in the duct, one on each side of the plate to measure the pressure differential. That gives a measure of how much gas passes the orifice plate in a period of time. Note that the orifice meter is oriented horizontally. The problem this creates is that liquid will collect in the horizontal pipe and back up at the upstream side of the orifice plate. That changes the duct cross-section and the flow characteristics of the gas passing through the duct and gives false readings.